The present invention relates generally to a transceiver assembly for use in a Doppler-based traffic radar system and, more particularly to a low visibility transceiver assembly having a reduced overall size or footprint.
Law enforcement officers have utilized Doppler-based traffic radar systems to monitor vehicle speeds and enforce traffic speed limit laws for many years. Throughout this period of time, numerous improvements in both the underlying technology and in the specific application of new processing techniques for the traffic radar systems themselves have afforded law enforcement officers greater flexibility and improved reliability in carrying out their duties. One such improvement evident in most traffic radar systems presently being marketed includes the capability to more accurately and reliably monitor the speed of certain vehicles while the patrol vehicle is either in a stationary or a moving mode of operation. In fact, present traffic radar systems can now accurately monitor the speed of vehicles approaching the moving patrol vehicle in an opposite lane, monitor the speeds of a group of target vehicles simultaneously and determine the fastest vehicle within the group, and even monitor the speed of a vehicle traveling in the same direction as the patrol vehicle independent of whether the vehicle is approaching or receding from the patrol vehicle, i.e., going faster or slower than the patrol vehicle. Importantly, each of these new or improved capabilities provide the law enforcement officer with a more complete picture of the traffic environment and thus, a more flexible and reliable basis for making more informed decisions.
Despite all the improvements in both the underlying technology utilized in these traffic radar systems and the radar systems themselves, only nominal attention has been given to improving the transceiver assemblies which form an important part of the overall radar system. Almost all transceiver assemblies utilized in the industry include a housing which receives microwave components (e.g., a turnstile and antenna horn) and circuitry (e.g., power supplies and pre-amplifiers) through a front or forward facing opening. Most commonly, a lens attached to the antenna horn for forming a radar wave into a beam extends through the front opening of the housing forming a seal between the lens and the housing. Other transceiver assemblies utilized in the industry include an additional cap which is placed over the portion of the lens extending from the housing. The cap is attached to the housing forming a seal between itself and either the lens or the housing. Examples of traffic radar systems which utilize these types of transceiver assemblies include the K-55, and the PYTHON, PYTHON Series II, and PYTHON Series II FS radar systems manufactured by MPH Industries, Inc., the assignee of the present invention. Other radar systems such as the EAGLE Series radar systems manufactured by Kustom Signals, Inc. and the STALKER Dual SL and STALKER DSR manufactured by Applied Concepts, Inc., among others, offer similar products.
In operation, transceiver assemblies are typically visibly mounted in a front and/or a rear windshield area of the patrol vehicle, e.g., to a dashboard or suspended from a headliner or window frame. Depending on the overall size or footprint, and placement of the transceiver assembly, the law enforcement officer""s line of sight could be obstructed and/or the visibility of the transceiver assembly could provide advanced warning of the presence of the officer and more importantly, the radar system itself. As indicated above and despite these known limitations of present state of the art transceiver assemblies, very little effort has been devoted to improving the transceiver assembly by reducing its overall size or footprint and visibility, or otherwise.
Recently issued U.S. Pat. No. 6,008,750 to Cottle et al., assigned to Decatur Electronics, Inc., addresses the limitations created by the overall size of transceiver assemblies in the industry and describes a transceiver assembly having a reduced footprint. The transceiver assembly in the Cottle et al. patent utilizes an off-the-shelf patch antenna which is positioned within a square housing having a forward facing opening covered by a square cap. The off-the-shelf patch antenna was selected for its reduced size, and more specifically its minimal depth, compared to the industry standard conical horn antennas which are typically on the order of three inches in length causing the overall size or footprint of a transceiver assembly to be quite large. The Cottle et al. patent further suggests that a reduction of this standard length horn antenna below one and three quarter inches is not practical due to the physical and operational limitations of conical horn antennas and turnstiles used therewith.
Accordingly, a need is clearly identified for a radar system and more specifically, a transceiver assembly utilizing a conical horn antenna having a reduced overall size or footprint which provides increased flexibility in its placement within the patrol vehicle thereby limiting obstructions to the law enforcement officer""s line of sight, and reduced visibility from outside of the patrol vehicle. Preferably, the radar system and transceiver assembly would significantly reduce, if not eliminate, the above limitations of present transceiver assemblies in an aesthetically appealing assembly.
A novel and improved transceiver assembly is provided for use in a Doppler-based traffic radar system for determining the speed of at least one target. The transceiver assembly includes a cover for receiving therein component parts of the assembly including at least one of an oscillator, a turnstile, a conical antenna horn and a lens, a mixer, and circuitry. In other words, the cover is positioned over at least some of the component parts of the transceiver assembly which are enclosed by a cap removably attached to the cover.
In accordance with an important aspect of the present invention, the cover is specifically designed to allow a radar wave to pass there through substantially unaffected. In other words, at least a portion of the cover is transparent electrically, i.e., only nominal losses due to attenuation are incurred as a result of passing through the cover. In order to minimize these losses, the material selected for the cover, and the thickness and shape of at least a portion of the cover through which the transmitted waves travel may be specifically selected. Advantageously, this allows the overall shape of the cover to be selected for purely aesthetic reasons, if desired. In addition to selecting a material, and thickness and shape of at least a portion of the cover, the color of the cover may be further selected to reduce the visibility of the cover, and necessarily the transceiver assembly when mounted in a patrol vehicle.
In accordance with another important aspect of the present invention, the transceiver assembly has an overall size or footprint which is smaller than previously thought possible in the industry. Advantageously, this smaller overall footprint provides several advantages including flexible placement of the transceiver assembly within the patrol vehicle in locations which heretofore may have been considered too small to accommodate the transceiver assembly (e.g., behind the rear-view mirror) thereby limiting obstructions to the law enforcement officer""s line of sight, and reduced visibility from outside of the patrol vehicle.
The ability to reduce the overall footprint of the transceiver assembly is attributable in the present invention to the selection and design of the component parts of the assembly. For example, the conical antenna horn and turnstile may be formed from a unitary material. In addition to limiting the size of the assembly, forming the antenna horn and turnstile from a unitary material also lowers the number of component parts requiring assembly and thus, manufacturing expenses. Further, the length of the conical antenna horn which is a significant component of the overall size of the assembly, may be limited in some embodiments to no more than one and three-quarter inches in length. Of course, variations of the length of the antenna horn and taper angle are possible in accordance with the broad teachings of the present invention.
In addition to reducing the overall size or footprint of the transceiver assembly in order to provide the above-noted advantages, the circuitry associated with the transceiver assembly may be modularized such that the circuitry may be tested apart from the transceiver assembly. More specifically, the circuitry may be separated from the microwave components of the transceiver assembly for testing. In this manner, the circuitry may be independently tested prior to assembly within the transceiver assembly or during troubleshooting if a failure were to occur.
In accordance with the broadest teachings of the present invention, the transceiver assembly may be used in a Doppler-based traffic radar system. These radar systems are well known in the industry and generally include a processing unit coupled to one or more transceiver assemblies for determining and displaying a speed of at least one target. As indicated above, examples of these traffic radar systems include the PYTHON Series, SPEEDGUN PLUS, and DS 3 radar systems manufactured by MPH Industries, Inc., the assignee of the present invention. The details of at least some of these radar systems are set out in U.S. Pat. No. 6,008,752, for example, and incorporated herein by reference. Other radar systems mentioned above such as the EAGLE Series systems manufactured by Kustom Signals, Inc. or the STALKER Series systems manufactured by Applied Concepts, Inc. are also available. The details of these radar systems are set out in U.S. Pat Nos. 5,504,488, 5,528,246, 5,570,093 and 6,198,42 which are each incorporated herein by reference.
Still other objects of the present invention will become readily apparent to those skilled in this art from the following description wherein there is shown and described a preferred embodiment of this invention, simply by way of illustration of one of the modes best suited to carry out the invention. As it will be realized, the invention is capable of other different embodiments, and its several details are capable of modifications in various, obvious aspects all without departing from the invention. Accordingly, the drawings and descriptions will be regarded as illustrative in nature and not as restrictive.